Compensating telescopic boom



Sept. 12, 1961 E GATES COMPENSATING TELESCOPIC BOOM 2 Sheets-Sheet 1 Filed Sept. 4, 1959 Sept. 12, 1961 E. GATES COMPENSATING TELEscoPIc Boom 2 Sheets-Sheer?O 2 Filed Sept. 4, 1959 we? 913W hired Sturm This invention relates to crane booms and particularly vto an extensible or telescopic boom.

It is necessary that a crane boom be supported in its angular position by cables or other members extending from an anchor point on the Adeck of the crane structure to a connection on the boom adjacent the upper end thereof. By so doing the boom is given the necessary strength to resist deflection when a load is suspended from the outer end of the boom without having to make the boom excessively heavy in construction.

The major object of this invention is to provide an extension or telescopic boom which includes an upper section from the upper end of which the load is suspended, and a supporting cable system extending between the deck andthe boom sections and which includes a reach of supporting cable connected directly between the decl; and the upper end of the boom; the system being arranged so that the length of such reach is compensated automatically as the boom is extended or contracted so that the angle of the boom is not alfected. By reason of this arrangement, no manually controlled adjustment of the length Aof the boom-supporting cable reach is required in order to maintain the boom at any desired angle irrespective of the extension or contraction thereof. At the same time, means is incorporated in the cable system so that the angle of the boom may be changed at any time without affecting the' compensating action.`

A further object of theinvention is to provide a practical, reliable, and durable compensating telescopic boom, and one which will be exceedingly effective for the purpose for which it is designed.

These objects are accomplished by means of such structure and relative arrangement of parts as will fully appear by a perusal of the following specication and claims.

ln the drawings:

lFIG. 1 is a side elevation of the telescopic boom in its contracted position, showing the compensating boomsupporting cable system connected thereto.

FIG. 2 is a plan view of the contracted boom detached, and partly broken away and in section.

3 is a side elevation of the boom partly extended, and including the compensating Vcable system.

Referring now more particularly to the drawings, and to the charactersof reference marked thereon, the crane essentially comprises aboom, -indicated generally at 1, and a deck 2, either of the stationary or turntable type, from which the boom projects and on which the boom supporting and load lifting cables, and their control means, are mounted.

The boom comprises a lower tubular section 3 and an upper tubular section f4 slidable in section 3. The sections are preferably of square form in cross section, but may be of any other form as long as the upper section cannot turn in the lower section. The section 3 at its lower end is provided with rigid depending ears 5 at its sides which support a transverse spindle 6. This spindle is journaled in other ears 7 mounted on and upstanding from the deck 2.

A two-way hydraulic cylinder unit is disposed within the boom, this unit comprising a cylinder 8 connected at its lower end to the spindle 6 and a piston rod 9 projecting from the upper end of the cylinder and connected at its upper end to a transverse spindle 10 mounted in the upper boom section adjacent its upper end. The necessary fluid conduits 11, which are connected to the cylinder adjacent its ends, lead from the lower end of the 'ice boom for connection to any suitable and conventional Huid-pressure supply and control system (not shown). By means of this arrangement, the boom may be extended or contracted as may be desired, and held in any position.

The self-compensating boom-supporting structure, which is a cable system, indicated generally at 12, holds the boom at a constant angle regardless of its extension or contraction, and is arranged as follows:

A cable 13, for each side of the boom 1, is secured at one end to an anchor point such as a Winch 14 of conventional character, and which is mounted on the deck 2 or on a frame 15 upstanding from the deck back of the boom 1. The cable leading from the winch passes about a pulley 16 mounted on the top of the frame 15 and extends thence forwardly in the form of a reach 17 to and about a pulley 1S on one side of the boom and which is mounted on the outer end of spindle 10. From this pulley, the cable extends rearwardly in the form of another reach 19 to and about another pulley 20 on frame 15, and which pulley is preferably adjacent and concentric with pulley 16.

From pulley 20, the cable 13 extends forwardly in the form of another reach 21, to and about a pulley 22 mounted on the side of boom section 3 at its upper end, said side being of course the same one as that on which the pulley 18 on the upper boom section 4 is disposed.

lFrom pulley 22, cable 13 extends rearwardly in the form of still another reach 23, to and about another pulley 24. This pulley is mounted in a bracket 25 secured to and projecting from the side of the upper boom section 4 adjacent the lower end thereof; said bracket passing through an elongated slot 26 in the corresponding side of the lower boom section 3 and of sucient length to allow of the full extending and contracitng movement of the upper boom section 4. From pulley 2'4, the cable 13 extends forwardly as a nal reach 27 to an anchor point, as at 28, on the side of the lower boom section 3 adjacent the pulley 22.

By reason of the above described cable mounting and reeving, and which includes the two pairs of cable reaches 17--19 and 23-27, any extension or contraction of the boom will cause an accompanying extension or contraction of one pair of such cable reaches, and a compensating contraction or extension of the other pair of reaches. As a result, the angle of the boom will always remain constant. The angle of setting of the boom may however be changed at any time, and as may be desired, by taking in or letting out the cable at the winch 14.

As indicated previously, there are two sets of the above described cable arrangements, one on and connected to each side of the boom, while utilizing a single winch v1li. rIhis not only has a stabilizing effect on the boom, but leaves ample space therebetween for the centrally disposed load lifting cable 29, which extends forwardly from a winch 30 on the frame 15 to and about a pulley 31 on the upper forward end of the boom section 4.

From the foregoing description it will be readily seen that there has been produced such a device as will substantially fulfill the objects of the invention, as set forth herein.

While this specification sets forth in detail the present and preferred construction of the device, still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention, as deiined by the appended claims.

Having thus described the invention, the following is claimed as new and useful, and upon which Letters Patent are desired:

1. In a crane, a mounting deck, a boom upstanding from the deck at an angle to the perpendicular, the boom escaneo comprising upper and lower sections mounted together for relative telescopic movement, means connecting the boom sections for extending and contracting the same, the lower section being mounted on the deck, and a boom supporting structure connected between the deck and both boom sections adjacent their upper ends at an acute angle to said sections and including automatically functioning means incorporated therewith so that the said angle of thc boom will remain unchanged with any extending or contracting movement of the upper boom section relative to the lower boom section.

E. In a crane, a mounting deck, a boom upstanding from the deck at an angle to the perpendicular, the boom comprising upper and lower sections mountedtogether for relative telescopic movement, means connecting the boom sections for extending and contracting the same, the lower section being mounted on the deck, a boom supporting cable, an anchor point for one end of the .cable mounted in connection with the deck behind the boom, an Vanchor point for the other end of the cable on the lower boom section adjacent its upper end, and means reeving said cable between one anchor point, the vupper boom section adjacent its upper end, the lower boom section adjacent its upper end, and the other anchor point so that the angle of the boom will remain unaffected with any extending or contracting movement of they upper boom section relative to the lower boom section and without altering the length ol' said cable with any such extending or contracting movement.

3. In a crane, a mounting deck, a boom upstanding from. the decl: at an angle to the perpendicular, the boom comprising upper and lower sections mounted together for relative telescopic movement, means connecting the boom sections for extending and contracting the same, the lower section being mounted on the deck, a boom supporting cable system comprising a cable, one anchor point for one end of the cable mounted in connection with the deck behind the boom, a second anchor point for the other end of the cable on the lower boom section adjacent its upper end, and means reeving the cable between the one anchor point, the upper end of the upper hoorn section and the second anchor point toprovide pairs of compensating cable reaches and including a irst pulley on the upper boom section adjacent its upper end, a second pulley mounted in connection with the deck adjacent the one anchor point, a third pulley mounted on the lower boom section adjacent the second anchor point, and a fourth pulley mounted on the upper boom section adjacent its lower end and below the third pulley; the cable passing forwardly from the one anchor point to and about the first pulley, then rearwardly to and about the second pulley, then forwardly to and about the third pulley, then rearwardly to and about the fourth pulley, and thence forwardly to the second anchor point.

4. A structure, as in claim 3, in which the first, third, and fourth pulleys are on one side of the boom with their axes transversely thereof; there being corresponding pulleys on the other side of the boom, with another cable similarly anchored and reeved on said other side of the boom.

5. A structure, as in claim 3, in which the lower boom section is tubular and the upper boom section is slidable therein; the lirst, third and fourth pulleys being outwardly of the boom on one side thereof, and a bracket for the fourth pulley rigid with and projecting laterally out from the upper boom section, the lower boom section having a longitudinal slot through which the bracket slidably projects.

6. ln a crane, a mounting deck, a boom upstanding from the deck at an angle to the perpendicular, the boom comprising upper and lower sections mounted together for relative telescopic movement, means connecting the boom sections for extending and contracting the same, the lower section being mounted on the deck, a boom supporting cable system'comprising a cable, one anchor point for one end of the cable mounted in connection with the deck behind theV boom, a second anchor point for the other end of the cable on the lower boom section adjacent'its upper end, and means reeving the cable between the anchor points and the upper boom section to provide pairs of compensating cable reaches arranged so that the angle of the boom remains unchanged with any extending or contracting movement Of the upper boom section relative to the lower boom section; said cable reeving means comprising a first pulley, means supporting said rst pulley from a point on the upper boom sectic-n adjacent the upper end thereof, a second pulley mounted in connection with the deck adjacent the one anchor point, a third pulley mounted on the lower boom section adiacent the second anchor point, and a fourth pulley mounted on the upper boom section adjacent` its lower end and below the third pulley; the cable passing forwardly from the one anchor point to Vand about the rst pulley, then rearwardly to and about the second pulley, then forwardlyto and about the third pulley, then rearwardly to and about the fourth pulley, and thence forwardly to the second anchor point, the pulleys being arranged so that the length of said cable between the anchor point remains unchanged with any extendor contracting movement of the upper boom section.

References Cited in the tile-of thispatent UNITED STATES PATENTS 2,698,696 Hughes Dec. 28, 1954 2,819,803 Obenchain Ian. 14, 1958 2,911,111 Grove i Nov. 3, 1959 2,928,493 Clements Mar; 15, 19,60 

